The invention relates to an apparatus for recovering the kinetic energy released during landing of an aircraft after contact with the ground, for ground and/or flight operation, comprising at least one energy converter for conversion of the kinetic energy into another energy form, where the energy converter is located in the area of the nose landing gear and/or in the area of the main landing gear of the aircraft.
In addition, the invention has as its subject matter a method for recovering the kinetic energy released during landing of an aircraft after contact with the ground for ground and/or flight operation.
In present-day aircraft, the kinetic energy released during the landing and subsequent braking process on the taxiway is converted by means of a braking system into heat of friction, where the thermal energy can no longer be used for other processes. The braking process is usually assisted by the aircraft engines being switched to reverse thrust during the braking process, which requires the use of additional energy which in the same way is lost for further energy use.
After the landing process, an aircraft nowadays is normally moved in the forward direction merely with the aid of the thrust of the main engines (so-called “taxiing”). Here the main engines are idling, that is operating far below the optimal operating state in view of the efficiency. A controlled backwards movement of an aircraft, for example, pushing back from the terminal (so-called “push-back”) must however be accomplished with motorized tow vehicles since the aircraft engines only deliver a pure forward thrust in regular operation.
The function of the pneumatic and electrical installations or systems of an aircraft in ground operation when the main engines are at a standstill is usually maintained by means of a so-called “Auxiliary Power Unit” (APU). An APU comprises a small gas turbine which is used to provide pneumatic and/or electrical energy for the onboard supply of the aircraft and which has a significantly reduced power compared to the main engines. The APU is usually located in the tail area of the aircraft fuselage. Starting the aircraft engines has also been accomplished hitherto by means of the pneumatic energy provided by the APU. In flight operation the necessary pneumatic, hydraulic and electrical energy is generated by means of the main engines. In ground operation the pneumatic and electrical energy is predominantly generated by means of the APU. The generated energy is required, inter alia, for maintaining the pressure in the aircraft cabin, the air-conditioning system, the anti-icing system, the de-icing system, tank pressurization, hydraulics, fresh water supply and other aircraft systems.
The emergency power supply during achieved with rechargeable batteries flight is nowadays and a so-called “Ram Air Turbine” (RAT). The “Ram Air Turbine” can, for example, be pivoted out on the underside from a wing or the aircraft fuselage. Consequently in an emergency situation ambient air flows onto the “Ram Air Turbine”. Electrical energy is generated by an electrical generator integrated in the “Ram Air Turbine” which is connected mechanically to an air screw of the “Ram Air Turbine”.
Further known from the prior art are landing gear systems for aircraft in which, for example an electric motor is integrated in the nose landing gear in order to enable maneuvering or rolling of the aircraft on the taxiway completely independently of the main engines and/or motorized tow vehicles. The electrical energy required to operate the electric motor is in turn taken from an APU. Aircraft fitted with such a system for rolling independent of the engines can achieve a considerable reduction in kerosene consumption compared with conventional aircraft which can only be maneuvered on the taxiway by means of the main engines or tow vehicles. Furthermore, motorized tow vehicles can be dispensed with, giving a considerable saving in costs, materials and staff.